<template>
  <div class="count">
    <h2>当前求和为：{{sum}}</h2>
    <select v-model.number="n">
      <option value="1">1</option>
      <option value="2">2</option>
      <option value="3">3</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script scoped>
export default {
  name: 'Count',
  data() {
    return {
      sum: 0, // 当前的和
      n: 1, // 用户选择的数字
    }
  },
  methods: {
    increment() {
      this.sum += this.n
    },
    decrement() {
      this.sum -= this.n
    },
    incrementOdd() {
      if(this.sum % 2) {
        this.sum += this.n
      }
    },
    incrementWait() {
      setTimeout(() => {
        this.sum += this.n
      }, 500);
    }
  }
}
</script>

<style scoped>
.count {
  background-color: #fafafa;
}
button {
  min-width: 40px;
  padding: 0 5px;
  margin-left: 6px;
}
</style>
